With the development of fifth generation communication systems, multiple mm-wave bands have been allocated worldwide including, but not limited to, spectra around 28 and 39 GHz. The availability of multiple such bands enables integrated frequency-reconfigurable transceivers to facilitate multiple-input and multiple-output (MIMO) frequency diversity and to reduce the cost of silicon (Si) integrated circuit (IC) components eliminating the need for a dedicated IC for each band. Such multi-band transceivers can achieve adequate performance with existing multi-band components, such as low noise amplifiers (LNA), power amplifiers (PA), and filters.
Gigahertz-band transceivers routinely employ frequency multipliers. Existing variable multiplier designs may use self-mixing or injection locking, but inherently suffer from low output power, insufficient harmonic rejection, and/or separate outputs for different tones. Some designs may use complex frequency generation circuitry that includes paralleled multiplier and amplifier chains, switched by a multiplexer to a single output. Use of more than one voltage-controlled oscillator (VCO) or a multi-mode VCO may also be considered, though this approach would be expected to undesirably affect system complexity, chip area, and/or phase noise performance.